This extract from an undated NSA document describes the planned capability of the automated malware injection system Turbine as extending to “potentially millions of implants”: see the Intercept article How the NSA Plans to Infect ‘Millions’ of Computers with Malware, 12 March 2014.

﻿(TS//SI//REL) A new intelligent command and control capability designed to manage a very large number of covert implants for
active SIGINT and active Attack that reside on the GENIE covert infras...